utils: smpp_mirror: temporarily munch SMPP delivery receipts

Just munch and log SMPP delivery receipts by now, don't mirror this, it
is going to break things in openbsc.

Follow up patch removes this and mirrors this SMPP message as a
SUBMIT_SM with esm_class = Delivery Acknowledgement.

Change-Id: I78e93bc4034679e238c8642ccf6a0e844b1d6d8b
1 file changed